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Multiple Codes After Changing Shift Solenoids and Trans Harness

SylvanFirestone

By SylvanFirestone
in Ask A GM Technician

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SylvanFirestone New Member

SylvanFirestone

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I have recently changed the shift solenoids and the trans harness on my 04 Silverado 1500 5.3l engine. Now I have like 31 different codes that have showed up while using my scanner as well as the ABS light and E-brake light coming on. Which those 2 lights are causing me to have shifting issues as well [truck acts like it is in limp mode] The codes are P0327, P0740, P0753, P0758, P0785, P2761, U1041, P0128, P0719, P2610, P0116, P0125, P0420, P0430, P0442, P2771, P1810, P1574, P0894, P0757, P0756, P0752, P0751, P0742, P0741, P0568, P0567, P0530, P0496, P0455, and U1000. Any help with this would be awesome. Please let me know if you need any more info.

Jsdirt Senior Enthusiast

Jsdirt

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My spidey senses tell me the new solenoid is internally shorted ... but before you dive back inside, go back and look at anything and everything you touched or moved, particularly wiring harnesses. One broken wire under intact insulation can do this - makes it lots of fun to find ... GM and their Chinese copper. I usually grab a single wire and pull on it in opposing directions - if the wire snaps in half, you found it. You shouldn't be able to pull copper apart with your bare hands, regardless of how crappy it is.

 

Also, if you unplugged the round plug on the transmission, make sure pins didn't get bent, or that female contacts didn't get shoved up into the plug where they won't make contact.

 

If that all checks out, unfortunately you're going to have to drop the pan again and search around for damaged wiring in there. IF that checks out, always suspect a new part. We have a saying in the automotive industry: " NEW means, Never Ever Worked." Parts quality is in the toilet these days, even straight from GM.

SylvanFirestone New Member

SylvanFirestone

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2 hours ago, Jsdirt said:

My spidey senses tell me the new solenoid is internally shorted ... but before you dive back inside, go back and look at anything and everything you touched or moved, particularly wiring harnesses. One broken wire under intact insulation can do this - makes it lots of fun to find ... GM and their Chinese copper. I usually grab a single wire and pull on it in opposing directions - if the wire snaps in half, you found it. You shouldn't be able to pull copper apart with your bare hands, regardless of how crappy it is.

 

Also, if you unplugged the round plug on the transmission, make sure pins didn't get bent, or that female contacts didn't get shoved up into the plug where they won't make contact.

 

If that all checks out, unfortunately you're going to have to drop the pan again and search around for damaged wiring in there. IF that checks out, always suspect a new part. We have a saying in the automotive industry: " NEW means, Never Ever Worked." Parts quality is in the toilet these days, even straight from GM.

Sounds like I am gonna have to check the wires from the oil pressure sensor down to the transmission. I wish I had a lift right about now lol. At some point this week I will crawl up under there and update as to what I find.

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SylvanFirestone New Member

SylvanFirestone

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On 6/21/2021 at 10:05 AM, SylvanFirestone said:

Sounds like I am gonna have to check the wires from the oil pressure sensor down to the transmission. I wish I had a lift right about now lol. At some point this week I will crawl up under there and update as to what I find.

Took the solenoids out and bench tested them as well as swapped solenoid a and b. Me and my dad also checked the plug that connects the trans harness to the main harness and it appears to be fine. Today or tomorrow, we will be checking all the wires on the main harness from the oil pressure sensor to the transmission and all the sensors and modules in between.

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Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted (edited)

Might be worth getting an AlldataDIY subscription for a year. That way you can look at wiring diagrams and try to find a common denominator with all those codes. Seen which systems are affected - could be one circuit powering all of that.

 

Before you get too deep in the wiring, check both fuse boxes for blown fuses - a blown fuse could to the same, if all those codes are related to components run on that same circuit.

Edited by Jsdirt
grammar

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